Change search
Refine search result
1234567 1 - 50 of 999
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Abbasi, Hamon
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Velayat park: En plats för gränsöverskridande möten mellan människor med olika socioekonomisk status2017Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Tehran, the capital of Iran has undergone major urbanization in the last century, which has caused uncontrollable urban growth. Poor regulation and control of this growth has given rise to environmental problems including high air and water pollution. In turn, this has led to urban growth towards the mountains in the north, where the environment is better. However, this pressure to develop in the north has increased segregation of the city and created a clear social division of class between the northern and southern parts of the City.

    In light of this, and in the context of Tehran as an extremely dense city with limited green space, the City sees a possibility in transforming an unused military airport in the southern districts of the city into a new urban park.

    This master thesis explores how to reclaim the 270Ha former airfield and develop it as an urban park with strengthened links to surrounding neighbourhoods.

    The work aims to gain an understanding of how large vacant areas can become successful public areas and green places in the community. The work is based on urban theory and site analysis and brings forward design proposals for the park.

    Analysis work is divided into an investigative and exploratory stage. The investigative part includes literature studies, data collection and mapping of the city’s urban morphological development, taking into account physical and socio-economic processes. The exploratory part consisted of inventories, site studies and interviews in Tehran, as well as integration analysis with space syntax to explore accessibility and connections in the new park.

    Throughout the study shows how and why the city has evolved and highlights a connection between living in the southern districts, which are low-income areas, with also having poor access to public and recreation areas.

    This analysis forms the foundations for the design proposal, visualizations and programs presented about how the area can be designed as a new urban city park.

    In conclusion, the study highlights that in order to be able to develop new places or renew existing area’s, consideration must be given to urban morphological development. This includes the socio-economic and socio-ecological process. It further concludes, that a ecological viewpoint together with a understanding of the physical environment, the urban landscape identity and the need of people in the context needs to be brought together to plan and create parks and urban spaces

  • 2.
    Abrahamsson, Lena
    et al.
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Human Work Science.
    Enander, Mats
    Olsson, Hans
    Luleå tekniska universitet.
    Ranhagen, Ulf
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Fallstudierapport: Iggesunds bruk. Efterbehandlingen. Arbetsrapport1993Report (Other academic)
  • 3.
    Abrahamsson, Lena
    et al.
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Human Work Science.
    Enander, Mats
    Luleå tekniska universitet.
    Olsson, Hans
    Luleå tekniska universitet.
    Ranhagen, Ulf
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Förstudie av massabalshanteringen vid Iggesunds kartongbruk: arbetsrapport1996Report (Other academic)
  • 4.
    Addie, G.R.
    et al.
    GIW Industries Inc..
    Roudnev, A.S.
    Weir Minerals North America.
    Sellgren, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Weir Minerals North America2007In: Hydrotransport 17: the 17th International Conference on the Hydraulic Transport of Solids ; [7 - 11 May 2007, Cape Town, South Africa, South African Institute of Mining and Metallurgy, 2007, p. 205-218Conference paper (Refereed)
    Abstract [en]

    The Hydraulic Institute has completed the task of developing a new ANSI/HI standard 12.1-12.6 (2005) for rotodynamic (centrifugal) slurry pumps covering nomenclature, definitions, applications, and operation. The standard provides examples of the different slurry pump types and contains an extensive section on pump and slurry definitions. The effect of slurry on pump performance is covered along with the pumping of froth. Reference is also made to ANSI/HI standard 9.6.7 (2004), which contains a new method for pump performance correction when handling viscous fluids. Classification of slurry services is established and then is used to determine limitations on velocities and total head per pump in order to obtain acceptable wear performance. The new service class, head per stage and other limits are directly related to capital and other cost considerations that will affect solids transport system economics. The writers review the contents of the new standard, highlight the main points, and discuss the reason for the slurry classification, corresponding limits and expected implications, particularly with respect to operating costs of the pumps in solids transport systems

  • 5.
    Addie, Graeme
    et al.
    Engineering and Research and Development, GIW Industries Inc.
    Carstens, M.
    GIW Industries Inc..
    Sellgren, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Visintainer, R.
    GIW Industries Inc..
    Whitlock, L
    Hydraulic Test Lab., GIW Industries Inc.
    Pipeline design characteristics of some industrial paste-like slurries2005In: Conference Proceedings - First Extractive Metallurgy Operators' Conference, The Australian Institute of Mining and Metallurgy , 2005, p. 147-154Conference paper (Refereed)
    Abstract [en]

    There is a wide variety of industrial pastes or non-settling slurries pumped in mining, dredging and reclamation projects as products, refuse and tails. The types and/or names of some of the common ones are alumina red mud, phosphate clays, tar sands mature fine tails, tar sands (CT) consolidated clays and fly ash. The pipeline performance or friction of these varies dramatically with the type, its concentration and the particulars of the actual slurry making it difficult to select pumping equipment and to design associated pipelines. The GIW Hydraulic Laboratory in Grovetown Georgia has tested a number of these slurries over the last 30 years for various mining customers. Where available in the public domain and/or where permission has been obtained, the results of those tests are presented in this paper in a form usable for pipeline and pump system designers and users.

  • 6.
    Addie, Graeme R.
    et al.
    GIW Industries Inc..
    Roudnev, Aleksander S.
    Weir Minerals North America.
    Sellgren, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    The new ANSI/HI centrifugal slurry pump standard2007In: Journal of the South African Institute of Mining and Metallurgy, ISSN 0038-223X, Vol. 107, no 6, p. 403-409Article in journal (Refereed)
    Abstract [en]

    The Hydraulic Institute has completed the task of developing a new ANSI/HI standard 12.1-12.6 (2005) for Rotodynamic (Centrifugal) Slurry Pumps covering nomenclature, definitions, applications, and operation. The standard provides examples of the different slurry pump types and contains an extensive section on pump and slurry definitions. The effect of slurry on pump performance is covered along with the pumping of froth. Reference is also made to ANSI/HI standard 9.6.7 (2004), which contains a new method for pump performance correction when handling viscous fluids.Classification of slurry services is established and then is used to determine limitations on velocities and total head per pump in order to obtain acceptable wear performance. The new service class, head per stage and other limits are directly related to capital and other cost considerations that will affect solids transport system economics. The writers review the contents of the new standard, highlight the main points, and discuss the reason for the slurry classification, corresponding limits and expected implications, particularly with respect to operating costs of the pumps in solids transport systems.

  • 7.
    Addie, Graeme R.
    et al.
    GIW Industries Inc..
    Sellgren, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    A first slurry standard and some implications for paste application2007In: Paste 2007: proceedings of the tenth International Seminar on Paste and Thickened Tailings / [ed] Andy Fourie; Richard Jewell, Perth: Australian Centre for Geomechanics, 2007, p. 153-162Conference paper (Refereed)
    Abstract [en]

    The Hydraulic Institute has just completed the task of developing a new ANSI/HI standard on Rotodynamic (Centrifugal) Slurry Pumps covering nomenclature, definitions, applications, and operation. The standard provides examples of all the different types of pumps available and has an extensive section on definitions. Slurries and their effect on performance and wear are covered. A slurry service class is established which then is used to limit velocities and head produced per pump to give acceptable wear. A special section deals with mechanical seals and a new method for determining flange loads is presented and guidelines are given for commissioning, start-up etc.The head limits and the performance derating are of special interest when centrifugal slurry pumps are applied to thickened tailings and paste-like slurries. For Newtonian liquids, the Hydraulic Institute's Viscosity Correction Method (ANSI/HI 2004) provides a procedure widely used for viscous effects on the performance. For the homogeneous flow of viscous slurries, the new slurry standard refers to an applicable viscosity to use with the method and to "consult the pump manufacturer for guidance regarding non-Newtonian slurry pump performance."Experimental performance results are presented here and applied to the viscosity correction method for a simulated tailings product slurry characterized by a fully sheared yield stress of about 100 Pa, evaluated from pipeline data. The pump was a GIW-LCC type three-vane all metal unit with a 0.3m-diameter impeller having an open shroud with a simple auger-like inducer. Results are also given for an underground hydraulic fill product characterized by a Newtonian kinematic viscosity which is 1300 times that for water. The different results obtained here point out the strong influence the rheological behavior has on the choice of pump size and the power requirement.

  • 8.
    Addle, Graeme R
    et al.
    GIW Industries Inc..
    Sellgren, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Design, selection, sizing and control considerations for cyclone feed slurry pumps1999In: Powder Technology, ISSN 0032-5910, E-ISSN 1873-328X, Vol. 104, no 3, p. 233-239Article in journal (Refereed)
    Abstract [en]

    Cyclone feed centrifugal slurry pumps in semi-autogenous grinding (SAG) mill and other cyclone feed circuits see coarse size slurries at high concentrations that can result in high wear if the pump is not designed, selected, sized and operated correctly. The high proportion of static head of the normal cyclone feed circuits usually results in a relatively flat system curve which in conjunction with the typically flat slurry pump curve results in large changes in operating flow with small changes in system head. When this is combined with the normal (or abnormal) fluctuations in the output from the mill upstream of the pumps, any shortcomings in the pump control system and/or matching of the pump means large fluctuations in flow and increased wear. This difficulty could be corrected by continuous variations in speed. A means of control by which the speed is changed in an appropriate way is suggested here. In this case then the pump-input power, the known water performance of the pump and the system flow, can be used to calculate an effective pump discharge pressure. By comparison with a calculated system head, the pump speed can be regulated such that the pressures are equal and the system stable for any practical variation of incoming flow or specific gravity.

  • 9.
    Alakangas, Lena
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Maurice, Christian
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Macsik, Josef
    Strategic services & Sustainable Development at Ecoloop.
    Nyström, Elsa
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Sandström, Nadia
    Luleå tekniska universitet.
    Andersson-Wikström, Alexandra
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Hällström, Lina
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Kartläggning av restprodukter för efterbehandling och inhibering av gruvavfall: funktion tillgång och logistik2014Report (Other academic)
  • 10.
    Ali, Jones
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Alisson, Hussein
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Gestaltningsprogram Murjek: Ett förslag på anpassning av småskaliga tågstationer avseende turism, funktion och tillgänglighet2017Independent thesis Advanced level (degree of Master (Two Years)), 40 credits / 60 HE creditsStudent thesis
    Abstract [en]

    Trafikverket plans to soon upgrade theplatform of Murjek station, a small-scale trainstation that constitute Jokkmokkmunicipality's only railway station alongMalmbanan and has clear links to touristdestinations. In connection with this, amapping of touristic aspects for smaller trainstations related to tourism shall be made andan associated design program for Murjekstation area will be developed.This method in this report consists of doing asystematic literature review, interviews andfield studies, which served as the base for themapping that has been done. The goal of thisreport is to, through the touristic aspects andthe design program, answer the followingscientific questions:How can a design proposal for a small-scaletrain station linked to tourism look like?● What features are important to create anaccessible and functional train station?● What parameters are important for a smallscaletrain station seen from a touristicperspective?How should Murjek station and thesurrounding station area be designed in orderto promote tourism development in asustainable way?● How can touristic experience values be metthrough the design of the station area?● What touristic aspects should be met in thedesign of Murjek station?Through following the method ofåtgärdsvalsstudier, the station area has beeninventoried and a summarized view of theshortcomings in the area has been compiled.Furthermore, measures of action based on theinterviews and theory have been developedand evaluated which has culminated in thetouristic aspects. These, along with the theoryfor the design of train stations, were the basisfor the design program.The compiled touristic aspects cover the areasof design, information, culture, art,functionality, and social aspects and aredesigned to be applicable to all small-scalestations linked to tourism. The design programis divided into three parts: the station area,the station building and the platform. All threeareas have been renovated and adapted to bemore accessible and functional based onexisting guidelines and to meet the touristicaspects developed.The design program embodies the practicalapplication of the touristic aspects and theexisting guidelines for functionality,accessibility, and design. This result is meantas a source of inspiration for other small-scalestations and demonstrates the possibility tocombine all of these elements into anattractive travel center that is well suited forall types of travelers, including persons withdisabilities and tourists.The report is geographically limited to Murjekand its vicinity and is limited to theparameters tourism, accessibility, andfunctional adaptation.

  • 11.
    Almqvist, Helena
    et al.
    Luleå kommun.
    Hanaeus, Jörgen
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Organic hazardous substances in graywater from Swedish households2006In: Journal of environmental engineering, ISSN 0733-9372, E-ISSN 1943-7870, Vol. 132, no 8, p. 901-908Article in journal (Refereed)
    Abstract [en]

    The concentrations of several selected organic hazardous substances were investigated in domestic graywater. In total, 41 of 81 organic hazardous substances were found in concentrations above the detection limits (nonylphenol and octylphenol ethoxylates, brominated flame-retardants, organotin compounds, polyaromatic hydrocarbons, polychlorinated biphenyls, phthalates, linear-alkyl benzene sulfonate, and triclosan). Moreover, total solids, biochemical oxygen demand (BOD7), chemical oxygen demand (COD), total nitrogen, total phosphorus, potassium, and sulphur were investigated and presented for graywater. Another objective was to suggest potential household sources for a selected number of organic hazardous substances. The present and past investigations reveal households to be obvious contributors of organic hazardous substances to municipal wastewater, and that graywater is an important media in this transport. The spreading derives from diffuse household sources like everyday activities (laundry, cleaning, etc.), the wearing down of things such as pipe material and interior fittings, and from airborne deposition.

  • 12.
    Al-Rubaei, Ahmed
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Long-Term Performance, Operation and Maintenance Needs of Stormwater Control Measures2016Doctoral thesis, comprehensive summary (Other academic)
  • 13.
    Al-Rubaei, Ahmed
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Engström, Malin
    Växjö Municipality.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Blecken, Godecke-Tobias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Long-term hydraulic and treatment performance of a 19-year old constructed stormwater wetland: Finally maturated or in need of maintenance?2016In: Ecological Engineering: The Journal of Ecotechnology, ISSN 0925-8574, E-ISSN 1872-6992, Vol. 95, p. 73-82Article in journal (Refereed)
    Abstract [en]

    Constructed stormwater wetlands (CSWs) are a commonly used measure for stormwater retention and quality treatment. However, although questions have been raised about the long-term performance of CSWs, only a few studies have targeted this issue and none have evaluated the performance of CSWs more than approximately 5–10 years old. Further, most studies have not examined the development of the long-term performance of CSWs but delivered a snapshot at a certain point of time. The present study investigated the performance of a 19-year-old CSW in Växjö, Sweden, treating stormwater from a 320-ha urban catchment. Besides removal of sediment from the CSW’s forebay, no other maintenance had been conducted. However, regular inspections had been performed. The results of the present sampling campaign were compared to two existing datasets collected at the same CSW after three years of operation in 1997 and nine years of operation in 2003. The CSW was found to provide efficient peak flow reduction and, depending on the event characteristics, also volume reduction. It still treated stormwater effectively: removal of Cd, Cu, Pb, Zn, TSS and TP event mean concentrations were between 89 and 96%, whereas mean concentrations of TN were reduced by 59%. The load removal efficiencies were even higher. Comparative analysis of the three monitoring periods based on the load removal efficiency revealed that the CSW, despite the lack of maintenance, performed more efficiently and stably for most pollutants compared to when newly constructed. This underlines the importance of the establishment and maturation of constructed wetland systems. Overall, the results showed that CSWs are resilient systems, which if designed well and regularly inspected to prevent major issues, can work efficiently for at least two decades.

  • 14.
    Al-Rubaei, Ahmed
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Engström, Malin
    Växjö Municipality.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Blecken, Godecke-Tobias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Long-term hydraulic performance of stormwater infiltration systems: a field survey2013In: NOVATECH 2013: Planning and Technologies for Sustainable Urban Water Management, 23 - 27 June 2013, Lyon, France., 2013Conference paper (Refereed)
    Abstract [en]

    This paper examined the factors influencing the long-term hydraulic performance of some stormwater infiltration systems (swale and two types of permeable pavements) in Växjö, southern Sweden. The infiltration capacities of 9 permeable pavements and 2 swales sites, all with different ages ranging from 1 year to 14 years, were measured using replicate double ring infiltrometers. The sites were either constructed of swale (2), interlocking concrete pavers (ICP) filled with gravel (2), concrete grid pavers (CGP) filled with gravel (3), or concrete grid pavers (CGP) filled with grass (4). The results of this study showed that the long-term behaviour of the infiltration capacity relies largely on the type and age of the system and the type of joint filling (gravel and grass). Furthermore, the study showed that the 11 year old concrete grid pavers filled with grass had the highest infiltration capacity (4.80 + 2.46 mm/min), whilst the 9 and 14 year old swales had the lowest infiltration capacity (0.10 + 0.00 mm/min).

  • 15.
    Al-Rubaei, Ahmed
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Engström, Malin
    Växjö Municipality.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Blecken, Godecke-Tobias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Long-term treatment efficiency of a constructed stormwater wetland: preliminary results2014Conference paper (Refereed)
    Abstract [en]

    Constructed stormwater wetlands (CSWs) are commonly used in Sweden and worldwide because of their high efficiency in urban stormwater management. However, questions have been raised about the long-term performance of CSWs. This study investigated the performance of a 19-year-old constructed wetland, which was designed to treat the stormwater from a 320-ha catchment located in the city of Växjö, southern Sweden. The system has not been maintained since its construction in 1994. The results of the present study were compared with results obtained from a previous study conducted by Växjö Municipality in 1997. The results showed that the CSW significantly reduced peak flows by 72%. High concentration reductions were found for Cd, Cr, Cu, Zn, Pb, TSS and TP (90, 89, 91, 90, 96, 96 and 86%, respectively). TN concentrations were reduced by 61%. The results indicated that lack of maintenance had no effect on the performance of wetland system during this long period of operation (19 years). In contrast, especially the removal of Cu and nitrogen was enhanced compared to 1997, which may be due to maturing of the system. The results show that CSWs are resilient systems, which (provided that design is sufficient) can work efficiently for at least two decades.

  • 16.
    Al-Rubaei, Ahmed
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Merriman, Laura S.
    Biological & Agricultural Engineering, North Carolina State University.
    Hunt, William F.
    Biological & Agricultural Engineering, North Carolina State University.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Marsalek, Jiri
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Blecken, Godecke-Tobias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Survey of the operational status of 25 Swedish municipal stormwater management ponds2017In: Journal of environmental engineering, ISSN 0733-9372, E-ISSN 1943-7870, Vol. 143, no 6, article id 05017001Article in journal (Refereed)
    Abstract [en]

    During the past 50 years, wet stormwater ponds have been constructed to reduce negative environmental impacts of urban stormwater discharges on receiving aquatic environments. However, in many jurisdictions there is little information on the current operational status of such ponds and their functioning. This paucity of information prompted a field survey of 25 Swedish municipal stormwater ponds, aged between 3 and 26 years. The pond survey focused on estimating the pond hydraulic loading and efficiency, the state of littoral vegetation, characteristics of bottom sediment in the inlet and outlet zones (sizes and the chemistry), and the overall operational pond status, including the access for maintenance. The hydraulic efficiencies of ponds were estimated for pond footprint shapes and relative locations of the inlets and outlets using literature data. The estimated hydraulic efficiencies correlated well with the pond length-to-width ratios and the ratio of the pond surface area to the impervious area of the runoff contributing catchment (i.e., the hydraulic loading). Littoral vegetation was inspected visually and found to be overgrown at some facilities, which impeded the maintenance access. Benthic sediments in ponds contained silt and clay (&lt;63&#x2009;&#x2009;&#x3BC;m" role="presentation" style="box-sizing: border-box; display: inline; line-height: normal; word-spacing: normal; word-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; position: relative;"><63  μm<63  μm), sand and gravel fractions, and when compared with the literature data, such sediments appeared relatively coarse. Chemical characteristics of sediments reflected anthropogenic (traffic) activities, but without excessive contamination warranting special disposal requirements. Of the 25 ponds surveyed, four were fenced off and inaccessible to machinery. In fact, the design of these four ponds was such that it made inspection and maintenance very difficult, which may pose potential risks to ponds operation. Fifty-four percent of the investigated ponds were in need of minor maintenance, primarily because of sediment and litter accumulation in their inflow and outflow sections. The fact that the inspection survey revealed relatively few minor issues that could be corrected easily demonstrates the importance of relatively simple regular inspections serving to detect minor problems at an early stage before they would seriously impact pond functioning. The above survey methodology should be helpful for developing similar low-cost surveys in other jurisdictions.

  • 17.
    Al-Rubaei, Ahmed Mohammed
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Engström, Malin
    Växjö Municipality.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Blecken, Godecke-Tobias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Effectiveness of a 19-Year Old Combined Pond-Wetland System in Removing Particulate and Dissolved Pollutants2017In: Wetlands (Wilmington, N.C.), ISSN 0277-5212, E-ISSN 1943-6246, Vol. 37, no 3, p. 485-496Article in journal (Refereed)
    Abstract [en]

    This study monitored the stormwater runoff quantity and quality treatment performance of a 6.8 ha 19-year old combined pond-wetland system, located in south Sweden, over one year. The mean volume reductions for 53 storm events for the pond and wetland were 40% and 28%, respectively, while the mean flow reductions were 60% and 76%, respectively. Pollutant concentrations in the influent to the wetland were highly variable. The pond-wetland system could efficiently remove an average of 91%, 80%, 94%, 91%, 83% and 92% of TSS, TP, particulate Cd, Cu, Pb, and Zn, respectively, whereas the removal of particulate and dissolved Ni was highly variable with an average of 67% ± 62% and −5% ± 41%, respectively. The removal of TN, NH4-N and NO3 + NO2-N was highly variable with an average of 45% ± 27%, 12% ± 96% and 45% ± 43%, respectively. These removal percentages are high in comparison to other studies and underline that relatively old systems can also provide efficient treatment. Although the pond accounted for a substantial reduction of pollutant concentration, the wetland significantly enhanced both the treatment performance and the peak flow reduction. This underlines that a combined pond/wetland system is a more beneficial solution than a pond only. The pollutant removal efficiency was significantly influenced by some factors including Antecedent Dry Days, seasonal variations, air temperature, retention times, rainfall depth and duration, and peak rainfall intensity.

  • 18.
    Al-Rubaei, Ahmed
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Stenglein, Anna Lena
    Blecken, Godecke-Tobias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Can vacuum cleaning recover the infiltration capacity of a clogged porous asphalt?2012In: WSUD 2012: Water Sensitve Urban Design - 21 - 23 February 2012, Melbourne Cricket Ground : building the water sensitve community, Barton: Institution of Engineers, Australia , 2012Conference paper (Refereed)
    Abstract [en]

    Objective: The main threat for the performance of porous asphalt is clogging leading to decreased infiltration capacity. Thus, we investigated the potential of vacuum cleaning to recover the infiltration capacity of clogged permeable asphalts which have been in use for several decades. The influence of road operation and maintenance measures on the results was discussed.Method: We investigated the hydraulic conductivity (HC) of two roads with porous asphalt in Haparanda and Luleå, Sweden, which had been in use for 28 years and 15 years, respectively. A lack of appropriate maintenance during their operating life had lead to significant clogging and thus malfunction. The roads were vacuum cleaned using a vacuum cleaner/sweeping truck combination. This technology is recommended as a maintenance option for porous asphalt. Before and after the vacuum cleaning, replicate HC measurements were conducted using double-ring infiltrometers.Result: Before vacuum cleaning, mean HC was <0.1mm/min in Haparanda and between 0.4 and 0.8 mm/min in Luleå. After vacuum cleaning, HC increased significantly in Luleå (between 1.1 and 7.1mm/min) while no significant increase was detected in Haparanda. Despite the improvement after vacuum cleaning, HC was still far lower than the initial HC after construction. Reasons for the different results in Haparanda and Luleå were identified; the road winter maintenance was of primary importance.Conclusion: Depending on the extent of clogging, vacuum cleaning has the ability to recover HC of porous asphalt. However, long term behaviour of the HC depends largely on the street maintenance, thus regular appropriate maintenance is preferable.

  • 19.
    Al-Rubaei, Ahmed
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Stenglein, Anna Lena
    Blecken, Godecke-Tobias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Long-term performance of a porous asphalt pavement in Luleå, Sweden: preliminary results2011Conference paper (Other academic)
  • 20.
    Al-Rubaei, Ahmed
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Stenglein, Anna Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Blecken, Godecke-Tobias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Long-term hydraulic performance of porous asphalt pavements in northern Sweden2013In: Journal of irrigation and drainage engineering, ISSN 0733-9437, E-ISSN 1943-4774, Vol. 139, no 6, p. 499-505Article in journal (Refereed)
    Abstract [en]

    The effect of clogging on the long-term infiltration capacity and porosity of two 18- and 24-year-old porous asphalts was examined by using replicate double-ring infiltrometer tests and analyzing asphalt core samples. Tests were carried out to see if high pressure washing and vacuum cleaning could restore the hydraulic performance. The infiltration capacity of the porous asphalts decreased substantially, primarily due to surficial clogging (0.50 +/- 0.26 in Lulea, Sweden, and 0.22 +/- 0.12 in Haparanda, Sweden, compared to initially > 290 mm min(-1)). In Lulea, washing and vacuum cleaning could partially restore the infiltration capacity (3.48 +/- 3.00 mm min(-1)), but in Haparanda, no effect was measured. The porosity was constantly between 16 and 18%. The difference of the long-term behavior and effect of cleaning in Lulea and Haparanda is primarily attributable to different street maintenance, age, and winter maintenance (application of fine gravel and/or sand). Although the infiltration capacity in Lulea was far below initial values, the asphalt still has the capacity to infiltrate an intense design rainfall (100 year average return interval, 15 min duration), underlining that porous asphalt can be a resilient feature also under nonfavorable conditions

  • 21.
    Al-Rubaei, Ahmed
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Blecken, Godecke-Tobias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Long-term hydraulic performance of stormwater infiltration systems2015In: Urban Water Journal, ISSN 1573-062X, Vol. 12, no 8, p. 660-671Article in journal (Refereed)
    Abstract [en]

    Despite the common use of stormwater infiltration systems, there is still only limited data available evaluating the long-term hydraulic function of such systems. The hydraulic performance of twelve stormwater infiltration systems (vegetated and unvegetated concrete grid pavers, unvegetated interlocking concrete pavers and grassed swales) was therefore investigated in field and laboratory environments in Växjö, Sweden. The systems investigated had not been subjected to regular maintenance to sustain infiltration capacity. Due to this, and the fact that, for most systems, an inappropriate joint filling material was used and (at the swales) there was severe compaction, most systems showed a reduced infiltration capacity. Despite this, especially the older vegetated systems, were still capable of infiltrating intense design rainfalls. This study showed the influence of some factors (type and age of the system, the type of joint filling material (grass and macadam) and the distance from the edge of the pavement) on the long-term behaviour of the infiltration capacity. In conclusion, there is a significant risk that existing stormwater infiltration systems are not working adequately in praxis. Proper implementation of construction and regular control by the inspecting authority has to be ensured.

  • 22.
    Altorkmany, Lobna
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Kharseh, Mohamad
    Civil Environmental Engineering Department, Chalmers University of Technology, Sweden.
    Ljung, Anna-Lena
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Lundström, Staffan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Effect of Working Parameters of the Plate Heat Exchanger on the Thermal Performance of the Anti-Bact Heat Exchanger System to Disinfect Legionella in Hot Water Systems2018In: Applied Thermal Engineering, ISSN 1359-4311, E-ISSN 1873-5606, Vol. 141, p. 435-443Article in journal (Refereed)
    Abstract [en]

    The objective of the current study is to analyze the effect of different working parameters on the thermal performance of the Anti-Bact Heat Exchanger system (ABHE). The ABHE system is inspired by nature and implemented to achieve continuous disinfection of Legionella in different human-made water systems at any desired disinfection temperature. In the ABHE system, most of the energy is recovered using an efficient plate heat exchanger (PHE). A model by Engineering Equation Solver (EES) is set-up to figure out the effect of different working parameters on the thermal performance of the ABHE system. The study shows that higher supplied water temperature can enhance the regeneration ratio (RR), but it requires a large PHE area and pumping power (PP) which consequently increase the cost of the ABHE system. However, elevate temperature in use results in a reduced PHE area and PP, which accordingly reduce the cost of the ABHE system. On the other hand, the EES-based model is used to study the effect of the length and the width of the plates used in the PHE on the RR and the required area of the PHE. Finally, taking into account the geometrical parameters, flow arrangement and the initial operating conditions of the PHE, the EES-based model is used to optimize the PHE in which its area is minimized, and the RR of the ABHE system is maximized.

  • 23.
    Altorkmany, Lobna
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Kharseh, Mohamad
    Civil Environmental Engineering Department, Chalmers University of Technology.
    Ljung, Anna-Lena
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Lundström, Staffan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Experimental and Simulation Validation of ABHE for Disinfection of Legionella in Hot Water Systems2017In: Applied Thermal Engineering, ISSN 1359-4311, E-ISSN 1873-5606, Vol. 116, p. 253-265Article in journal (Refereed)
    Abstract [en]

    The work refers to an innovative system inspired by nature that mimics the thermoregulation system that exists in animals. This method, which is called Anti Bacteria Heat Exchanger (ABHE), is proposed to achieve continuous thermal disinfection of bacteria in hot water systems with high energy efficiency. In particular, this study aims to demonstrate the opportunity to gain energy by means of recovering heat over a plate heat exchanger. Firstly, the thermodynamics of the ABHE is clarified to define the ABHE specification. Secondly, a first prototype of an ABHE is built with a specific configuration based on simplicity regarding design and construction. Thirdly, an experimental test is carried out. Finally, a computer model is built to simulate the ABHE system and the experimental data is used to validate the model. The experimental results indicate that the performance of the ABHE system is strongly dependent on the flow rate, while the supplied temperature has less effect. Experimental and simulation data show a large potential for saving energy of this thermal disinfection method by recovering heat. To exemplify, when supplying water at a flow rate of 5 kg/min and at a temperature of 50 °C, the heat recovery is about 1.5 kW while the required pumping power is 1 W. This means that the pressure drop is very small compared to the energy recovered and consequently high saving in total cost is promising.

  • 24. Altorkmany, Lobna
    et al.
    Nordell, Bo
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Overview of legionella bacteria infection: control and treatment methods2009Conference paper (Other academic)
  • 25.
    Altorkmany, Lobna
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Nordell, Bo
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Overview of Legionella Bacteria Infection: Control and Treatment Methods2009Conference paper (Refereed)
    Abstract [en]

    Since the first recognized outbreak of Legionnaires' disease (LD) in 1976, it has become an increasing problem around the world especially in poor countries. Legionella (L) causes an estimated 15,000 annual cases of pneumonia in USA, and leads to death in about 20% of the cases. L is found worldwide in both natural and artificial environments e.g. spa pools, cooling towers. It infects people by inhaled contaminated aerosols that can transmit several km. The optimal temperature for L growth is 20-45C. Control of L is therefore an important health issue. Many treatment methods are used; biocides, ionisation, ozone, UV-radiation, pressure, and thermal treatment. Only thermal treatment can completely eliminate L, which is killed almost instantly at 70C. Current paper gives an overview of the Legionella problem and treatment methods.

  • 26.
    Amara, S.
    et al.
    Unité de Recherche en Energies Renouvelables en Milieu Saharien (URER/MS).
    Benyoucef, B.
    Unité de Recherche Matériaux et Energies Renouvelables (URMER), Université de Tlemcen.
    Nordell, Bo
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Touzi, A.
    Unité de Recherche en Energies Renouvelables en Milieu Saharien (URER/MS).
    Benmoussat, A.
    Unité de Recherche Matériaux et Energies Renouvelables (URMER), Université de Tlemcen.
    Experimental study of a concentration heating system with optical fiber supply2009In: Abstract book and proceedings : Effstock 2009: 11th International conference on Thermal Energy Storage for Energy Efficiency and Sustainability / [ed] Signhild Gehlin, Stockholm: Energi- och Miljötekniska Föreningen / EMTF Förlag , 2009Conference paper (Refereed)
    Abstract [en]

    The buildings thermal function is important to provide comfort to its tenants. This means to provide cooling during hot seasons and/or heating in cold season. Current study concerns modelling of a new design of thermal photo sensors that results in a more efficient heating for Tlemcen site, Algeria.

  • 27.
    Amara, S.
    et al.
    Unité de Recherche en Energies Renouvelables en Milieu Saharien (URER/MS).
    Benyoucef, B.
    Unité de Recherche Matériaux et Energies Renouvelables (URMER), Université de Tlemcen.
    Nordell, Bo
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Touzi, A.
    Unité de Recherche Matériaux et Energies Renouvelables (URMER).
    Benmoussat, A.
    Unité de Recherche Matériaux et Energies Renouvelables (URMER), Université de Tlemcen.
    Experimental study of a domestic hot water storage tank thermal behaviour2009In: Abstract book and proceedings : Effstock 2009: 11th International conference on Thermal Energy Storage for Energy Efficiency and Sustainability / [ed] Signhild Gehlin, Stockhiolm: Energi- och Miljötekniska Föreningen / EMTF Förlag , 2009Conference paper (Refereed)
    Abstract [en]

    Much work has been carried out on hot water storage during the last 20-30 years, particularly on solar heat applications. Theoretical and experimental studies on the internal heat transfer have been made at laboratory scale and at larger scales. Current study, which was conducted in order to understand the stratification phenomena, involved an experimental study on the thermal behaviour in a hot water tank during charging and discharging for domestic hot water storage. Results showed no effect of stratification due to the injection fluid from the bottom of the tank and the effect of mixed convection induced by the temperature difference which created a mixture inside the tank, where the temperature was uniform across the height, and the apparition of stratification due to the fact of discharge from the bottom of the tank.

  • 28.
    Amara, Saidi
    et al.
    Unité de Recherche Matériaux et Energies Renouvelables (URMER), Université de Tlemcen.
    Baghdadli, T.
    Unité de Recherche Matériaux et Energies Renouvelables (URMER), Université de Tlemcen.
    Nordell, Bo
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Khimulu, R.
    Unité de Recherche Matériaux et Energies Renouvelables (URMER), Université de Tlemcen.
    Solar System Design for Water Treatment: Antibacterial Heat Exchanger (ABHE)2017In: Innovative Healthcare Systems for the 21st Century / [ed] Hassan Qudrat-Ullah, Peter Tsasis, Springer International Publishing , 2017, p. 167-180Chapter in book (Refereed)
    Abstract [en]

    Current study concerns the fundamental problems to eliminate pathogens that are responsible for waterborne diseases. These illnesses, which have followed man throughout history, are described by occurring symptoms such as diarrhea and nausea. The various organisms identified within this document as waterborne bacterial pathogens are, e.g., Legionella (causes Pontiac fever), Salmonella (typhoid fever), and Yersinia (plague). Several control methods are available for water disinfection: biocide, ultraviolet light sterilization, copper–silver ionization, ozonation, etc., but only thermal treatment can eliminate bacterial pathogens, which are killed almost instantly at 70 °C. The current chapter describes water disinfection by a solar concentrator combined with a heat recovery system that reduces the heat demand. Though this study is made for a small system (160 l of hot water per day), the system can be enlarged (more hot water and more solar collector area), and the results are thus valid also for such larger systems. Here experiments of water treatment by a solar concentrator are summarized and analyzed where the temperature exceeds 80 °C at the outlet of the heat exchanger.

  • 29.
    Amara, Sofiane
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Corrigendum to “Using Fouggara for Heating and Cooling Buildings in Sahara” (Energy Procedia 6 (2011), 55–64)2011In: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 6, p. 825-Article in journal (Refereed)
  • 30.
    Amara, Sofiane
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Novel and ancient technologies for heating and cooling buildings2011Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The basic issue of this thesis concerns one of the fundamental problems of the future of our society: How to meet the energy requirements for a large and growing world population while preserving our environment? This question is important for the world and the answers are complex and interwoven.Conventional energy sources, fossil and fissile, are polluting in the present and in the future: they erode the environment and their resources are limited. Renewable energy (hydro, wind, solar, geothermal) constitutes a minimum of pollution in the different energy systems. The technologies for using renewable energy are well known though further development and progress are made. This development also requires behavioural change, adaptation, and above all political will. The transition from an economy based on fossil energy to an economy based on renewable energy appears necessary for the protection of the environment. The cost of renewable energy is often represented as an obstacle but remains competitive in the long run.The development and availability of renewable energy, which varies because of its spatial and temporal distribution, require an adaptation of lifestyle, habits, habitat design (passive bioclimatic houses), urban planning and transportation.The focus of this thesis was to apply renewable energy in an area with hot summers and cold winter, a climate like that in the northwest of Algeria. In order to provide improved comfort in the buildings and also economic development in this area, the energy demand for heating and cooling was analyzed in the ancient city of Tlemcen. To supply domestic hot water and space heating, water must be simultaneously available at two different temperature levels. Cold water temperature, close to that of the atmosphere, and hot water between 50 and 60°C. An interesting feature of the preparation of hot water is the small variation of requirements during the year, unlike that to heating. The preparation of hot water is one of the preferred applications of solar energy in the building for several reasons. For this reason an experimental study of the thermal behaviour of a domestic hot water storage tank was undertaken. The phenomena that affect the thermal behaviour of tank especially the coupling between the solar collector and storage tank was studied. This study included concentrating solar collector in which optical fibers were used to transport the energy to the storage tank. Another technology was introduced and developed for the heating and cooling of buildings in the desert involving an existing ancient irrigation system called Fouggara. The novel idea is to use the Fouggara as an air conditioner by pumping ambient air through this underground system. Then air at a temperature of about 21°C would be supplied to the building for heating in the winter and cooling in the summer. This study shows the feasibility of using this ancient irrigation system of Fouggara and contributes to reducing and eliminating the energy demand for heating and cooling buildings in the Sahara desert.

  • 31.
    Amara, Sofiane
    et al.
    Université de Tlemcen, BP 119 Tlemcen.
    Baghdadli, Tewfik
    Université de Tlemcen, BP 119 Tlemcen.
    Knapp, Samuel
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Nordell, Bo
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Legionella Disinfection by Solar Concentrator System2017In: Renewable & sustainable energy reviews, ISSN 1364-0321, E-ISSN 1879-0690, Vol. 70, p. 786-792Article in journal (Refereed)
    Abstract [en]

    The current study concerns the fundamental problems of Legionnaires disease. Four decades after Legionnaires' bacteria was first identified there is still a low level of clinical awareness. Humans are infected by inhalation of aerosolized water and/or soil contaminated with the bacteria. Several control methods are available for water disinfection: biocide, ultraviolet light sterilization, copper-silver ionization, ozonation etc. but only thermal treatment can completely eliminate Legionella, which is killed almost instantly at 70 °C. The current paper describes Legionella disinfection by a solar concentrator combined with a heat recovery system that reduces the heat demand. Though this study is made for a small system (160 l of hot water per day) the system can be enlarged (more hot water and more solar collector area) and the results are thus valid also for such larger systems. Here experiments of water treatment by a solar concentrator are summarized and analyzed where the temperature exceeds 80 °C at the outlet of the heat exchanger.

  • 32.
    Amara, Sofiane
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Benmoussat, A.
    Renewable Energy Research Unity in Saharien Middle, ‘URER/MS’.
    Benyoucef, B.
    Renewable Energy & Materials Research Unity, ‘URMER’.
    Nordell, Bo
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Requirements energy estimate of heating & cooling for a dwelling in the site of Tlemcen2007Article in journal (Refereed)
  • 33.
    Amara, Sofiane
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Nordell, Bo
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Benyoucef, B.
    Université de Tlemcen, BP 119 Tlemcen.
    Using fouggara for heating and cooling buildings in Sahara2011In: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 6, p. 55-64Article in journal (Refereed)
    Abstract [en]

    In order to utilise naturally stored heat or cold from the ground, seasonal temperature variations are required. The reason is that the ground temperature is then warmer than the air temperature during winter and colder during summer. The heating and cooling demand in North Africa varies considerably with the greatest cooling demand in the East and the greatest heating demand in the West. In parts of Algeria the mean temperature difference between the coldest and warmest month is greater than 20 °C, which is favourable. In current work it was shown that the ancient Fouggara system, even today would be interesting for heating and cooling of buildings in the Sahara desert.

  • 34.
    Amara, Sofiane
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Nordell, Bo
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Benyoucef, B.
    Université de Tlemcen, BP 119 Tlemcen.
    Benmoussat, A.
    Université de Tlemcen, BP 119 Tlemcen.
    Concentration heating system with optical fiber supply2011In: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 6, p. 805-814Article in journal (Refereed)
    Abstract [en]

    This paper reports on an experimental realization and field testing of a recently proposed solar fiber optic mini dish light concentrator connected to a hot water accumulator. The prototype dish is 150 cm in diameter. In repeated test the collected and concentrated sunlight was transported in a one millimeter diameter optical fiber to a selective surface in the storage tank. This surface absorbs the radiation which remains trapped inside as it heat exchanges with tank fluid which temperature can reach 70 °C.

  • 35.
    Amofah, Lea Rastas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    A small scale wastewater treatment system adapted to nutrient recovery in cold climate: performance and possible sorbents2007Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Waterbodies are impaired by, among other things, discharge from onsite small- scale wastewater (WW) treatment systems. Hence, these systems need to be updated to improve the effluent quality and the reuse of nutrients within society. The objectives of this thesis were to find suitable sorbents for a small scale WW treatment system, to investigate the performance of a willow bed in cold climate and to evaluate the function of a proposed WW treatment system adapted to sustainable development in cold climate.Column experiments were performed to study the ammonium adsorption and desorption of clinoptilolite. Laboratory scale studies were conducted to estimate the phosphorus (P) retention of blast furnace slag (BF slag). Further, a full-scale WW treatment system was implemented in northern Sweden to evaluate the function of the system and its units over 16 months. The system comprised of a willow bed and two parallel P filters, namely BF slag and Filtralite-P. A stream of primarily treated WW from a village was pumped to the treatment system.The results from the column experiments showed that ammonium adsorption of the studied clinoptilolite and the desorption of previously adsorbed ammonium was too low to be an economically reasonable alternative for WW ammonium retention in small-scale WW treatment systems.The investigated weathered and coarse-grained BF slag had a low WW P retention, with the overall P sorption below 100 mg P/kg. Therefore, the material is not suitable for P retention. Fresh and fine-grained BF slag demonstrated to be an effective P sorbent in laboratory experiments. However, the release of sulphuric compounds from the BF slag was extensive and may hinder its utilisation as P sorbent.Filtralite-P was found to be a promising P sorbent with a WW P sorption of about 370 mg P/kg at the end of the full-scale experimental period, and still with remaining capacity to retain P.The willow bed functioned as a treatment step due the reduction of nutrients, solids and BOD, and there was no significant difference in winter and summer performance. Climatic conditions seemed not to be a hindrance for willow beds in northern Sweden. However, the stemwood produced in the willow bed would replace only a small fraction of a household’s energy need for heating and warm water.In the full-scale study, the treatment system with BF slag filter attained neither of the protection levels given by Swedish Environmental Protection Agency (SEPA) during the experimental period. The Filtralite-P treatment line fulfilled the requirements of the low protection level by SEPA for the 1 year operating period and the requirements of the high protection level for 2 months. The need of maintanance in the studied treatment system was small and the operation was steady.

  • 36.
    Amofah, Lea Rastas
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Towards sustainability of environmental protection: recovery of nutrients from wastewater filtration and the washing of arsenic contaminated soils2012Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Conventional methods for wastewater treatment and remediation of the sites withcontaminated soils focus on protection of human health, receiving waters and theenvironment. Towards this end, these methods concentrate on the reduction or removal of polluting substances, and therefore, are not well suited for creating resources through the recovery of nutrients, energy and decontaminated soils. Hence, a new, more sustainable approach is promoted in this thesis and, besides meeting the protection requirements, takes into consideration the resources that can be recovered from the treatment processes, keeping in mind the energy use during such a recovery. To achieve this goal, a better knowledge of wastewater and contaminated soil treatment approaches needs to be developed, from a resource recovery perspective.In this thesis project, laboratory, pilot-scale and full-scale investigations were conducted to study phosphorus (P) sorption in blast furnace slag (BF slag) filters. Further, ammonium adsorption by, and desorption from, clinoptilolite was studied in laboratory columns. A full-scale wastewater treatment system, comprising a willow bed followed by two parallel P–filters with BF slag and Filtralite® P media was examined for the wastewater treatment efficiency, nutrient accumulation in willow biomass, and biomass production. In a similar way, laboratory, pilot-scale and full-scale investigations were conducted to examine arsenic (As) removal from As contaminated soils using physical separation and chemical extraction. Finally, the decontamination of the extraction effluents (contaminated by As) was studied by adjusting pH and adding a coagulant, iron chloride.Pollutant mobilisation and immobilisation were affected by pH, the organic mattercontent, redox potential, time (process duration) and temperature. Results showed that pollutants in the studied media have complex characteristics in terms of charge of species and redox speciation, and therefore, no general conclusions addressing all the conditions studied could be given. The P sorption capacity of BF slag was reduced by outdoor storage and weathering, and the content of organic substances in sewage seemed to have a more negative impact on the sorption process when using weathered BF slag. Arsenic mobilisation from As contaminated soils was affected by pH, the content of organic substances, and redox potential and the nature of these effects depended on the polluting chemicals (i.e. wood preservatives) and the content of calcium in the soil. Extractions at elevated temperatures facilitated high As mobilisation from the contaminated soils for short contact times, assuming that the extraction solution features vital for As mobilisation were not altered, and the fastest As mobilisation was achieved by using an acid oxalate citrate solution rather than reductive or alkaline extraction solutions at room temperatures.In the full-scale treatment system, the willow bed efficiently reduced the content of total suspended solids and biodegradable organic matter in the influent wastewater and prevented the clogging of downstream phosphorus filters during the one year of operation. The Filtralite® P treatment train simultaneously removed over 90 and 70% of BOD and P, respectively, during the experimental period, and therefore, fulfilled the requirements for the low protection level over the period of one year, except for tot-P excesses during the snowmelt period. In the case of tot-N reduction (50%), the high protection level was achieved. On the other hand, the treatment system with BF slag did not fulfil requirements for either low or high protection level, because the coarse-grained BF slag was inefficient in retaining P and the concentrations of oxygen consuming compounds were elevated downstream of the filter.The studied methods for recovering resources through treatment of wastewater and contaminated soils demonstrated a potential for improving environmental sustainability of these processes. Even though the willow bed did not accumulate nutrients from the fed wastewater to a high degree, it facilitated nutrient recovery in other treatment steps located downstream. Fresh, fine-grained BF slag showed capacity to recover P from wastewater, which was comparable to that of other efficient P sorbents. The BF slag material released high amounts of sulphuric compounds during the initial loading phase which consequently increased the concentration of oxygen consuming compounds in the filter effluent. Thus, the use of BF slag for P retention is not recommended when the effluent is discharged to sensitive receiving waters. Natural clinoptilolite studied showed a high capacity for adsorbing ammonium from the pre-treated wastewater, at low operating temperatures. Hence, the clinoptilolite filter has a potential to enhance N retention during the plant dormancy or prior to the maturity of willow beds when N retention is needed. However, the recovery of ammonium was limited by the inefficient desorption process using tap water without recycling the eluate. Fertigated willows grew nearly as well as in the south of Sweden, but in the highly loaded horizontal flow willow bed, the potential to produce biofuel was limited. To recover nutrients, willow clones with lateral growth are preferable. 90% of nutrients accumulated in the above-ground parts of willows could be recovered from the experimental site operated over three growing seasons, particularly when using dense planting and annual harvesting prior to leaf fall.Soil treatment, comprising the exclusion of the fine soil fraction prior to the chemical extraction with strong extraction agents applied at an elevated temperature, was efficient in decontaminating soils, even for short contact times. However, this treatment procedure results in an incomplete soil recovery (i.e. the recovered mass of soil after decontamination is appreciably smaller than the soil mass prior to decontamination), consumes a high amount of energy and lowers the soil quality, which limits the potential end-use of the decontaminated soil. The alkaline extraction effluents could be decontaminated at a pH of 4-5 with the addition of a coagulant. Also, the treatment of alkaline extraction effluents was facilitated by the exclusion of the fine soil fraction from the chemical extraction step. The use of acid oxalate-citrate extraction solution was judged infeasible because the decontamination of such extraction solution is complicated due to the high pH buffering and complexing capacity of the solution.

  • 37.
    Amofah, Lea Rastas
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Hanaeus, Jörgen
    Nutrient recovery in a smallscale wastewater treatment plant in cold climate2006In: Vatten, ISSN 0042-2886, Vol. 62, no 4, p. 355-368Article in journal (Other academic)
    Abstract [en]

    An onsite wastewater treatment plant at Brändön, north of Luleå, receiving primarily treated wastewater from a village, was operated and investigated during one year. The wastewater flow was 0.5 m3/d. The main treatment steps were a prefilter, mainly to distribute the flow, a vegetation filter consisting of two different clones of Salix and two phosphorus filters with Filtralite-P and blast furnace slag (BF slag) operated in parallel. The willow bed reduction of BOD7 was in average about 80% and of phosphorus (P) and nitrogen (N) 20-30%. The main mechanism was believed to be filtration in the bed. The reduction through plant uptake was minor. The Filtralite-P filter reduced BOD7, P and N with 67%, 72% and 20%, respectively. The BF slag filter reduced P and N with 53% and 3%, respectively. The release of sulphuric compounds from the BF slag filter increased the BOD7 content in the effluent. The Filtralite-P system achieved the requirements of the normal protection level given by the Swedish Environmental Protection Agency but not all of the requirements of the high protection level. The BF slag system did not fullfil the requirements of the two protection levels.

  • 38.
    Amofah, Lea Rastas
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Mattsson, Jonathan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Hedström, Annelie
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Willow bed fertigated with domestic wastewater to recover nutrients in subarctic climates2012In: Ecological Engineering: The Journal of Ecotechnology, ISSN 0925-8574, E-ISSN 1872-6992, Vol. 47, p. 174-181Article in journal (Refereed)
    Abstract [en]

    Conventional methods for wastewater treatment emphasise protecting human health, receiving waters and the environment. Consequently, they are generally designed to reduce pollutant levels and are not well-suited for creating resources. This paper describes a new, more sustainable and energy-efficient approach to wastewater treatment that satisfies health and environmental standards while also facilitating resource recovery. A full-scale compact willow bed was intensively fertigated with domestic wastewater in a cold climate to examine biomass production, the recovery of nutrients in willow biomass, and wastewater treatment. The performance of the willow bed was assessed for two years, covering three growing seasons. The studied frost-tolerant willow clones produced good biomass yields per unit area (6–7 ton dry matter/ha and year) under intensive fertigation with dense planting and continuous harvesting. The biomass yield of willow species exhibiting vertical growth seemed to be greater than that for lateral growth species in the dense stands studied. In contrast to biomass production, nutrient recovery was facilitated by intensive fertigation, continuous harvesting and less dense planting with a horizontally growing willow clone. The estimated nitrogen accumulation in above-ground biomass was 210 kg/ha and that of phosphorus was 30 kg/ha. 90% of the accumulated nutrients in the above-ground biomass were removed from the site during the experimental period. However, the quantity of nutrients accumulated in the willow biomass represented only a small fraction of the loaded or removed amount. The willow bed was shown to be an efficient prefilter for reducing the abundance of particulate and organic matter, leaving the bulk of the remaining nutrients in forms that could be recovered in subsequent treatment steps.

  • 39.
    Amofah, Lea Rastas
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Maurice, Christian
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Bhattacharya, Prosun
    Kungliga tekniska högskolan, KTH.
    Chemical extraction of As from a polluted soil2008In: Arsenic in the environment - Arsenic from nature to humans: Book of Abstracts, 2008, p. 205-Conference paper (Other academic)
  • 40.
    Amofah, Lea Rastas
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Maurice, Christian
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Bhattacharya, Prosun
    KTH-International Groundwater Arsenic Research Group, Department of Land and Water Resources Engineering, Royal Institute of Technology (KTH),.
    Extraction of arsenic from soils contaminated with wood preservation chemicals2010In: Soil & sediment contamination, ISSN 1532-0383, E-ISSN 1549-7887, Vol. 19, no 2, p. 142-159Article in journal (Refereed)
    Abstract [en]

    Three soil samples contaminated by chromated zinc arsenate (CZA) or chromated copper arsenate (CCA) were investigated in a laboratory scale to study As mobilization and to identify a chemical agent that could be used in soil washing to extract arsenic. Besides high As extraction, the cost, occupational health issues and technical aspects were considered when selecting the chemical. Arsenic is strongly bound to CZA/CCA soils; only ∼50% of the tot-As was removed from water-washed soils. High Fe or Al mobilization is not necessarily indicative of high As removal from CZA/CCA soils. A high Cu/As-ratio and a large amount of soluble Ca in the soil hampered As extraction. The high ratio can be an indication of stable Cu-arsenates in soil. Calcium can react with the extraction agent or with As during extraction. Sodium hydroxide, dithionite with citrate (and oxalate) (dithionite solutions), and oxalate with citrate were the most efficient chemicals for removing As from the soils. The disadvantages of using these strong chemicals are: a high cost (oxalate with citrate); damage to equipment (dithionite solutions); an adverse impact on occupational health (dithionite solutions); or a deterioration in soil quality after extraction (NaOH and dithionite solutons). Phosphate, solutions based on NH2OH·HCl, or citrate were not efficient in mobilizing As from the soils.

  • 41.
    Amofah, Lea Rastas
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Maurice, Christian
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Kumpiene, Jurate
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Bhattacharya, Prosun
    Department of Land and Water Resources Engineering, Royal Institute of Technology.
    The influence of temperature, pH/molarity and extractant on the removal of arsenic, chromium and zinc from contaminated soil2011In: Journal of Soils and Sediments, ISSN 1439-0108, E-ISSN 1614-7480, Vol. 11, no 8, p. 1334-1344Article in journal (Refereed)
    Abstract [en]

    Purpose: Normal soil washing leave high residual pollutant content in soil. The remediation could be improved by targeting the extraction to coarser fractions. Further, a low/high extraction pH and higher temperature enhance the pollutant removal, but these measures are costly. In this study, the utility of NaOH, oxalate-citrate (OC) and dithionite-citrate-oxalate (DCO) solutions for extracting of arsenic, chromium and zinc from contaminated soil were assessed and compared. In addition the effects of NaOH concentration and temperature on NaOH extractions, and those of temperature and pH on OC and DCO extractions, were evaluated. Materials and methods: A two-level, full-factorial design with a centre point was implemented. Two factors, concentration and temperature,were evaluated in NaOH extractions, and pH and temperature for OC and DCO solutions. In all cases, the extraction temperature was 20°C, 30°C and 40°C. The studied NaOH concentrations were 0.05, 0.075 and 0.1 M. The pH in OC solutions was 3, 5 and 7, and in DCO solutions, 4.7, 6.3 and 6.7. Water-washed and medium coarse soil fraction of arsenic, chromium and zinc contaminated soil was agitated for 15 min with the extraction solution. Results and discussion: In NaOH extractions, the temperature and (less strongly) NaOH concentration significantly affected As and Cr mobilisation, but only the latter affected Zn mobilisation. Both pH and temperature significantly (and similarly) influenced As and Cr mobilisation in OC extractions, while only the pH influenced Zn mobilisation. In contrast, the extraction temperature (but not pH) influenced As, Cr and Zn mobilisation in DCO extractions. Conclusions: For all extractants, mobilisation was most efficient at elevated temperature (40°C). None of the extractants reduced the soil's As content to below the Swedish EPA's guideline value. Use of DCO is not recommended because dithionite has a short lifetime and residual arsenic contents in DCO-extracted soil are relatively high. Instead, sequential extraction with NaOH followed by OC solutions (affording significant reductions in As, Cr and Zn levels in the soil with short extraction times) at 40°C is recommended

  • 42.
    Andersson, Elina
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Eriksson, Anette
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Valhallen: Konceptuell utformning av en multianläggning i Torsby med analys av tak- och fasadmaterial ur ett hållbarhetsperspektiv2017Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
  • 43. Andersson, O.
    et al.
    Hellström, Göran
    Nordell, Bo
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Recent UTES development in Sweden2000In: Proceedings: TERRASTOCK 2000, 8th International Conference on Thermal Energy Storage : University of Stuttgart, Germany, August 28th until September 1st, 2000 / [ed] Martin Benner, Stuttgart: Universität Stuttgart , 2000, p. 75-80Conference paper (Refereed)
  • 44. Andersson, Olle
    et al.
    Johansson, Sam
    Nordell, Bo
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Innovative and cost-effective cold storage applications in Sweden: IEA Annex 71994Report (Other academic)
  • 45. Andersson, Olof
    et al.
    Hellström, Göran
    Nordell, Bo
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Heating and cooling with UTES in Sweden: current situation and potential market development2003In: Proceedings: Futurestock 2003, 9th International Conference on Thermal Energy Storage : Warsaw, Poland, September 1 - 4, 2003, Warszawa: PW Publishing House , 2003, p. 207-215Conference paper (Refereed)
    Abstract [en]

    Underground Thermal Energy Storage (UTES) applications have slowly gained acceptance on the Swedish energy market. Two UTES concepts are successfully implemented; the ATES (aquifer storage) and the BTES (borehole storage) systems. Also snow storage in pits or caverns has reached a commercial status. The number of ATES has steadily grown to 40 large-scale plants at the end of 2002. The systems are usually designed for cold storage in district cooling application, but industrial process cooling is also common. The economical potential in terms of straight payback time is usually very favourable. However, there is still a certain risk for operational problems that might jeopardize the calculated profit. Well clogging problems and system control remain as R&D issues to be solved. From a legislation point of view any ATES application needs a permit. The process of obtaining a permit has become complex and time-consuming since a new act on environmental assessment was put into effect in 1999.BTES systems are normally used in smaller applications. At the end of 2002 there were more than 200 installations comprising more than 10 boreholes. The majority of these are applied for space cooling of commercial or institutional buildings and for process cooling within the telecommunication sector. From a technical point of view, BTES are much simpler to construct and operate than ATES. Furthermore, they can be applied in almost any kind of geology. Another advantage compared to ATES is that the permitting procedure is much simpler. The major market obstacle is that the profitability is not always acceptable if calculated as a straight payback time. To increase the market potential, there is a need for further R&D on improvement of borehole heat exchangers and of more effective drilling methods.Snow storage is still a new technology though the Sundsvall snow storage plant has been operated successfully for several years. This good example has inspired several pre-studies of new snow storage plants. These have shown that snow storage is feasible in various sizes and in different applications.

  • 46. Andersson, Sören
    et al.
    Abyhammar, Tomas
    Nordell, Bo
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Full-scale multiple well heat storage system for experiment and demonstration1983In: Proceedings - International Conference on Subsurface Heat Storage in Theory and Practice, Statens råd för byggnadsforskning , 1983, p. 610-615Conference paper (Refereed)
  • 47.
    Andersson, Sören
    et al.
    AIB Consulting Engineers.
    Eriksson, Anders
    AIB Consulting Engineers.
    Nordell, Bo
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Heat storage in rock: multiple well system1981Report (Other academic)
  • 48. Andersson, Sören
    et al.
    Eriksson, Anders
    Nordell, Bo
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Säsongslagring av värme i berg1981In: Byggnadskonst, ISSN 0007-7593, Vol. 73, no 11, p. 45-47Article in journal (Other (popular science, discussion, etc.))
  • 49.
    Andersson, Sören
    et al.
    Swedish Council for Building Research.
    Johansson, Alf
    Swedish Council for Building Research.
    Nordell, Bo
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Åbyhammar, Tomas
    Swedish Council for Building Research.
    A borehole heat store in rock: pilot trials in Luleå and preliminary design of a full-scale installation1983Report (Other academic)
  • 50. Andersson, Sören
    et al.
    Åbyhammar, Tomas
    Nordell, Bo
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Multiple well system for seasonal heat storage at Luleå1983In: Väg- och Vattenbyggaren, ISSN 0042-2177, no 4, p. 10-11Article in journal (Other (popular science, discussion, etc.))
1234567 1 - 50 of 999
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf